Question 1

Which of the following statements best explains why Pelagibacter ubique, with a surface area-to-volume (S/V) ratio of 22, exchanges nutrients and wastes more efficiently than E. coli, which has an S/V ratio of 4.5?

Accepted Answer

A higher S/V ratio means more surface area relative to volume, allowing faster exchange of materials per unit volume.

Question 2

Which of the following is NOT a universal property of all cellular life forms?

Accepted Answer

Dependence on a host cell for replication

Question 3

A scientist isolates a microbe that lacks a nucleus, has ether-linked membrane lipids, and can survive in extremely high temperatures. To which domain does this organism most likely belong?

Accepted Answer

Archaea

Question 4

Which of the following best describes why viruses are excluded from the universal tree of life?

Accepted Answer

Viruses lack ribosomes and do not possess ribosomal RNA genes.

Question 5

Which of the following cell wall components is unique to Gram-negative bacteria?

Accepted Answer

Lipopolysaccharide (LPS)

Question 6

A patient is infected with a bacterium that survives treatment with lysozyme. Which cell wall feature most likely explains this resistance?

Accepted Answer

Presence of pseudomurein with $$\beta-1$$,3 glycosidic bonds

Question 7

Which of the following best explains why endospores are a concern in medical sterilization procedures?

Accepted Answer

Endospores are highly resistant to heat, radiation, and chemicals, making them difficult to destroy.

Question 8

Which of the following is a function of the bacterial capsule or slime layer?

Accepted Answer

Helping bacteria adhere to surfaces and form biofilms

Question 9

Which of the following statements about the cytoplasmic membrane is correct?

Accepted Answer

It is composed of a phospholipid bilayer with embedded proteins and is selectively permeable.

Question 10

Which of the following best describes the difference between bacterial and archaeal cell membranes?

Accepted Answer

Bacterial membranes have ester-linked fatty acids, while archaeal membranes have ether-linked biphytanyl chains.

Question 11

A Gram-positive bacterium is stained using the Gram stain procedure. What is the expected result and why?

Accepted Answer

It will appear purple due to its thick peptidoglycan layer retaining the crystal violet stain.

Question 12

Which of the following structures is involved in bacterial motility?

Accepted Answer

Flagella

Question 13

Which of the following is a property shared by all living cells but NOT by viruses?

Accepted Answer

Ability to carry out metabolism

Question 14

Which of the following best describes the function of lysozyme in the context of bacterial cell walls?

Accepted Answer

Lysozyme cleaves $$\beta-1$$,4-glycosidic bonds in peptidoglycan, leading to cell lysis.

Question 15

Which of the following is a correct statement about microbial evolution?

Accepted Answer

All cellular organisms undergo evolution over generations.

Question 16

Which of the following is a distinguishing feature of prokaryotic cells compared to eukaryotic cells?

Accepted Answer

Prokaryotic cells lack membrane-bound organelles such as nuclei and mitochondria.

Question 17

Which of the following best explains why smaller cells have a higher surface area-to-volume ratio?

Accepted Answer

As cell radius decreases, surface area decreases by $$r^2$$ but volume decreases by $$r^3$$, increasing the S/V ratio.

Question 18

Which of the following is a function of pili in bacteria?

Accepted Answer

Facilitating genetic exchange between cells (conjugation)

Question 19

Which of the following is true regarding the composition of archaeal cell walls?

Accepted Answer

Some archaea have pseudomurein, which contains $$\beta-1$$,3 glycosidic bonds and is resistant to lysozyme.

Question 20

Which of the following is a correct statement about microbial communities?

Accepted Answer

Environmental conditions and nutrient resources strongly influence the composition of a microbial community.

Foundations of Microbiology: The Microbial World and Cell Structure

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